A chuck device having a looseness preventing mechanism is proposed as a chuck device having a structure described in Japanese Patent Application No. 2001-260708 (patent publication 1) assigned to the present assignee. Incidentally, since the structure thereof is the same as that of a first embodiment of the invention, the structure will be described with reference to FIGS. 1 to 4.
In such a chuck device having a looseness preventing mechanism, a rotary sleeve 1 is rotated so that a plurality of jaws 3 inserted into a hole 2a formed at a tip end of a body 2 is slidingly opened and closed; a tool 4 is clamped by the jaws 3; ratchet teeth 5 forming an annular shape are provided on the body 2; an annular rotary member 17 engaged with the jaws 3 and rotated together with the rotary sleeve 1 is fitted around the body 2 inside of the rotary sleeve 1; a retainer spring member 7 that is detachably engaged with the ratchet teeth 5 is arranged outside of the ratchet teeth 5; the retainer spring member 7 is provided so as to rotate around the ratchet teeth 5 together with the rotation of the rotary member 17; the retainer spring member 7 is mounted on the rotary member 17 by a convex and concave engagement means; and a holder portion for holding the condition that the engagement between the ratchet teeth 5 and the retainer spring member 7 is held and the disengagement between the ratchet teeth 5 and the retainer spring member 7 is held is provided.
By the way, in such a chuck device, it is proposed to manufacture the above-described body of light alloy such as aluminum in order to meet the requirement of weight reduction. However, since the ratchet teeth are formed by machining the ratchet teeth directly to the body, if the body is made of light alloy such as aluminum, then the ratchet teeth themselves are made of light alloy.
However, since the ratchet teeth are continuously and repetitively engaged with the retainer spring member made of steel, if the ratchet teeth are made of light alloy such as aluminum that is softer than the steel, the ratchet teeth are easily worn due to the continuous and repetitive engagement so that the looseness preventing mechanism does not work. This is disadvantageous in durability and maintenance.
Although a publication of Japanese Patent Application No. 2002-024495 (patent publication 2) assigned to the present assignee discloses a point for applying a coating on surfaces of the body and the ratchet teeth to thereby prevent the wear of the above-described ratchet, it is currently demanded to enhance the durability of the ratchet teeth more.
Patent Publication: Japanese Patent Application No. 2001-260708
Patent Publication: Japanese Patent Application No. 2002-024495